Neuropathic pain syndromes are often difficult to treat. Neuropathic pain occurs following injury of the peripheral and central nervous system. Patients with these pain syndromes have various types of pains (constant pain, paroxysms of pain, evoked pain), which are variable in severity. Neuropathic pain may be accompanied by variable degrees of associated sensory and motor deficits. These pain syndromes are known for they poor responsiveness to standard pain treatments, including opiate analgesics. Recent reports suggest that systemically administered local anesthetics provide pain relief in these syndromes. However it is not established if the analgesic responses are dose and serum concentration related. This project proposes to study the relation of pain relief obtained with intravenous lidocaine and lidocaine serum concentration. In this study the concentration-response curve will be established. Results of this study will provide information how optimally to dose lidocaine for treatment of these severely painful and treatment resistant pain syndromes.